The present invention relates in general to apparatus for manipulating paper signatures or objects of like nature. More particularly, the invention pertains to apparatus for forming a shingle running at a relatively lower velocity from incoming documents traveling at a very high velocity along a path in serial, spaced-apart relation with the through-put rate (in documents per hour) being equal in both the incoming stream and the outgoing shingle.
While the invention to be claimed in this application pertains principally to slowing down and shingling incoming documents by apparatus generically useful in a variety of different machines, the major portions of the drawings and description from applicant's above-identified parent application will be presented here for the sake of completeness and to make clear one specific environment.
Although the invention in certain aspects is not so limited, it is aimed toward achieving, and is embodied in, a high speed quarter folder. As is known in the printing art, newspaper presses conventionally include folding and transport units which bring out multiple sheet, single folded assemblies in an overlapped running shingle. The assemblies are called "signatures" and their folded edges are called "spines". The signatures in a running shingle usually move with the spines as leading edges and with each signature set back slightly (here called the shingle setback SSB) from the one which precedes it so that they travel in overlapped relation. A single fold signature may sometimes be called a "half signature"; when it is folded again about a medial line perpendicular to its spine, it becomes a quarter signature. By cutting at the original spine edge, a quarter signature may be turned into a booklet wherein each page is one quarter of an original sheet of paper. A quarter folder makes the second fold in a half signature to convert it into a quarter signature.
Almost universally, half fold signatures exit from a printing press, or they come from any other source, as a running shingle--for the reasons that the shingle is less flexible than individual signatures, and a high rate of through-put in items per unit time (e.g., signatures per hour) can be obtained with a lower conveyor speed in comparison to transporting signatures spaced out to travel one at a time.
When a given operation, such as quarter folding, must and can only be performed on signatures one at a time, however, then a spaced-out stream of successive signatures is required. In such cases, the documents from a stack or an incoming shingle are separated and accelerated to produce a spaced-out stream. In other instances, the documents created in or coming from a processing device (for example those from a high speed press prior to shingling) arrive in a spaced stream. There is a need to convert them into a shingle so that the same through-put rate is obtained at a lesser physical velocity. Conversion or "shingling" apparatus of the prior art, for example, the known Archimedes spiral buckets, are not only space-consuming, expensive and unreliable but wholly impractical at through-put rates on the roder of 72,000 documents per hour.